A geophysical study of a drumlin in the Åsnen area, Småland, south Sweden

Abstract: The sediment composition of drumlins in the Åsnen area in Småland, south Sweden is poorly studied. Excavations are being planned with intention to study the internal architecture and composition of these drumlins. As a preliminary investigation this thesis was done to determine the sediment depths in the tail of a drumlin at Rörvik gård, situated on Vemboö in Lake Åsnen. To determine the sediment depths three geophysical methods were carried out on the drumlin: (i) resistivity (cves), (ii) electromagnetic slingram and (iii) induced polarization effect measurements. Using the data acquired from these measurements, models presenting maximum and minimum potential depths to the bedrock were interpreted. The results indicate that the drumlin has varying sediment depths and undulating bedrock with the sediment on top being independent from the form of the bedrock. Sediment depths of 2m to 8m were found in the drumlin according to the minimum interpretation, and depths of 2-15+ m according to the maximum interpretation. Due to equivalence problems that come with the three selected geophysical methods, it is suggested that drilling samples are suited to solve the problem, providing much more accurate interpretations. It is also suggested that the geophysical method seismic refraction studies could potentially be another choice of method to be used in similar studies.